5 Seconds of Summer vs. Alex & Sierra – Pop Clash

5 Seconds of Summer's 'Amnesia' breaks our hearts a little every time we hear it, but it's quickly proving to be a fan favorite. For the third week in a row, the Aussies have snagged the Pop Clash title, most recently beating out Iggy Azalea's 'Fancy.' This round, 5SOS is up against 'The X Factor' stars Alex & Sierra's 'Scarecrow.' Who do you think should win Pop Clash?

Although 5 Seconds of Summer burst onto radio waves with their bombastic 'She Looks So Perfect,' we can't resist the heartbreakingly honest lyrics of 'Amnesia.' Listening to 5SOS wish away their happy memories is enough to make anyone tear up a little. However, the ballad proves the guys are just as amazing stripped-down than they are in a punk-pop anthem like 'Don't Stop.'

On the other hand, we can't help but start tapping our toes the second Alex & Sierra's 'Scarecrow' comes on. With its upbeat rhythm, sunny harmony and -- of course -- amazing vocals, music like this is exactly why the duo won 'The X Factor.' Like 5SOS, Alex & Sierra possess an uncanny ability to tap into a specific emotion. In this case, it gives us a glimmer of hope.

Who should win this week's Pop Clash? You can vote for 5SOS or Alex & Sierra once an hour until the polls close at 3PM ET on July 28.